In the field of this invention it is known that the receiver performance in wireless cellular telecommunication systems relies on the estimate of the impulse response of the overall channel which includes the transmitter pulse, the radio channel, and the receiver selectivity filtering.
From the publication “Iterative channel estimation using soft decision feedback”, by Magnus Sandell et al., Global Telecommunications Conference, 1998. GLOBECOM 1998. The Bridge to Global Integration. IEEE, Volume: 6, 1998, pp. 3728-3733, iterative channel impulse response estimation is known using soft decision feedback. In this known technique, channel impulse response estimation is improved through an iterative process which increases the number of known symbols in a received modulated signal by iteratively feeding back successive tentative decisions from an equaliser to a channel impulse response estimator.
However, this approach has the disadvantage that a great part of the complexity of the technique depends on the complexity of the equalizer, which may dramatically increase with the number of points in the modulation constellation.
A need therefore exists for iterative channel impulse response estimation using noise estimate wherein the abovementioned disadvantage may be alleviated.
Patent specification WO 01/61950 describes a method channel impulse response estimation using whitening filters in the noise estimate. In this method, a plurality of channel impulse response and noise sample estimates are needed for each iteration and the whitening filters introduce delay and added complexity.